#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    float x,y1,y2,y3,y4;
    x = 1.0/4;
    y1 = cos(x);
    y2 = 1 - y1;
    y3 = sin(x/2);
    y4 = 2*y3*y3;
    return 0;
}
